Rolling mill with roll deflection bi-dimensionally controlled

ABSTRACT

The present invention is generally directed to a rolling mill in which the supporting means are arranged in the middle region of the roll body of the working roll with their length(s) not longer than that of the roll body of the working roll. The supporting means supports or abuts against the middle and lateral roll supports at their central region in the axial direction during the operation of the rolling mill so as to provide central support to the roll supports. As a result, the middle and lateral roll supports and hence the rolls will not deflect or bend under the action of rolling force.

FIELD OF THE INVENTION

The invention generally relates to a rolling mill for producing plateand strip, and in particular to a rolling mill in which two-dimensionalcentral support is automatically formed so as to control the roll'sflexure, thereby the rolled plate and strip have very high thicknessprecision in cross section.

BACKGROUND OF THE INVENTION

Generally, there are a variety of kinds of rolling mills for rollingplate and strip, and they are classified according to the number ofrolls into the two-high mill, the four-high mill and the cluster mill,but the most commonly used rolling mills are the four-high mill, the HCmill and the cluster mill and so on. For two-high type, four-high typemills, there exist many disadvantages, the main disadvantage is that:when a piece to be rolled passes the mill stand, since the downwarddriving devices are located at the necks of the rolls, the rolls arecaused to have larger bending deformation, and the deformations of therolls will result in the thickness error in the cross section of therolled piece (rolled plate and strip), thus seriously affecting thequality of the rolled piece. To solve the above problem, the method ofincreasing the diameter of the rolls has to be adopted, and for afour-high mill, also the method of increasing the diameter of thesupporting rolls has to be adopted. However, as the diameter of therolls increases, it is certain to cause the rolling forces to abruptlyincrease, and the increase of the rolling forces in turn causes anincrease of the bending deformation of the rolls.

The cluster mills include integral housing type mills and open typemills (as shown in FIGS. 1, 2), Japanese Patent 54-1259 discloses acluster mill which adopts a tower-like roll system. Of course, suchrolling mills all have the advantage of high rigidity, but in a clustermill, the portions of the mill frame which contact the supporting rollsstill have bending deformation under rolling forces, thus causing theflexural deformation of the working rolls and affecting the uniformityof the thickness of rolled piece as a result.

The solution to the problem of the roll's flexural deformation to reduceor eliminate the effect of the roll's flexural deformation on thethickness of rolled piece consists in the control of the shape of theclearance between the working rolls to make the flexural deformation ofthe working rolls not to be affected by the change of rolling forces. AChinese Patent (application number 89101393, issue number CN 1013250B)discloses “A rolling mill with rolls of small flexure and highrigidity”. To achieve above object, according to the patent, thesupporting rolls at the outermost layer of the tower-like roll systemare supported on the roll supports in the form of a mufti-section beam;rolling forces acting on the working rolls are transmitted respectivelyto the upper and lower roll supports via the roll systems; the verticalcomponent of the force borne by the roll supports are transmitted to themill frame via the downward driving or upward driving devices or similarelements such as pads; the number of the downward driving or upwarddriving devices is at least two, and the positions of the downwarddriving or upward driving devices are in the middle region of the axisof the working roll on the roll supports. It can be seen, the solutionof that patent can make the flexural deformation of the roll supports inthe vertical plane not vary with the rolling forces in the main, thuseffectively reducing the thickness error in the cross-section of therolled piece. However, for the cluster mills with tower-like rollsystems, the force transmitted from the working rolls to theintermediate rolls has vertical and horizontal components, therefore theperipheral supporting rolls also bear significant horizontal componentforce. For the rolling mill disclosed in Chinese Patent 89101393, thehorizontal component force causes the roll supports to have horizontalflexural deformation, thus causing the axis of the supporting rolls, theintermediate rolls and even the working rolls to have larger flexuraldeformation.

As stated above, to solve the problem of flexural deformation of theworking rolls of a cluster mill, it is not only necessary to reduce theflexural deformation produced by the vertical component force, but alsothat produced by the horizontal component force, that is, it is obligedto solve the problem of deformation in two-dimensional directions, sothat a working roll can be held straight and the thickness precision inthe cross-section of the rolled piece can be increased.

SUMMARY OF THE INVENTION

Therefore, the invention is aimed to solve the problem of thetwo-dimensional flexural deformation of the rolls, namely, the rollingmill of the invention can reduce not only the flexural deformation invertical direction, but also that in horizontal direction. Accordingly,the object of the invention is to provide a high-precision rolling mill,as compared with the prior art, when the rolling mill of the inventionis subjected to the rolling force, the flexural deformation of the rollscan be greatly reduced, resulting in the reduction of the thicknesserror in the cross-section of the rolled piece and the increase of thedimension accuracy of the rolled piece.

To achieve the above-mentioned object, there is provided a rolling millfor rolling plate and strip comprising: a mill frame; an upper rollsystem and a lower roll system; and an upper middle roll support, anupper lateral roll support, a lower middle roll support and a lowerlateral roll support. The mill frame is of a frame type and is able tobear rolling forces, and all parts and components of the rolling mill,such as the roll systems, are incorporated in the frame. The rollsystems are so arranged as to be of a tower-like configuration. The rollsystem is composed of three parts, a working roll, supporting rolls andintermediate rolls; the upper and lower supporting rolls disposed at theoutermost layer of the roll system are respectively supported on theupper and lower middle roll supports and the upper and lower lateralroll supports in the form of a mufti-section beam, and the upper middleroll support and the upper lateral roll support can be moved up and downif necessary to adjust the magnitude of the clearance between the rolls.The mill frame, the roll supports, the central supporting means betweenthe middle roll supports and the lateral roll supports, the centralsupporting means between the frame and the middle roll supports and thecentral supporting means between the frame and the lateral roll supportscommonly form a two-dimensional central supporting system. The lateralroll supports automatically press tightly against the side walls of theframe under the action of horizontal component force. The centralsupporting means is disposed on at least one of the upper and lower rollsupports, and is arranged in the region near the middle part of the rollbody axis of the working roll with its length being not longer than thelength of the roll body of the working roll. The central supportingmeans includes driving devices and horizontal pads; there are at leasttwo driving devices disposed above the upper middle roll support andplaced in the mill frame, the lower middle roll support is supported byhorizontal pads. Both the driving devices and the horizontal pads arearranged in the region near the middle part of the roll body axis of theworking roll. In the rolling mill of invention, there are also disposedupper and lower vertical pads along a horizontal direction, which arerespectively positioned between the side surfaces of the upper and lowerlateral roll supports and the mill frame. Under the action of horizontalcomponent force, the lateral roll supports press tightly against theside walls of the mill through the vertical pads, thus being centrallysupported in the horizontal direction so as to prevent flexuraldeformation due to horizontal component force. In the rolling mill ofthe invention, horizontal pads are disposed between the middle rollsupports and the lateral roll support to further provide central supportto the lateral roll supports in the vertical direction. The shape of themill frame is mated with that of the combined roll supports.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention will be described in detail inconnection with accompanying drawings, and the object of the inventionwill become more apparent from the following description:

FIG. 1 is a schematic view of a conventional rolling mill;

FIG. 2 is a schematic view of a conventional open type cluster mill;

FIG. 3 is a schematic view of a conventional cluster mill disclosed in aJapanese Patent;

FIG. 4 is a front sectional view of the rolling mill in accordance withthe invention;

FIG. 5 is a sectional view of the rolling mill taken along line A—A inFIG. 4;

FIG. 6 is a sectional view of the rolling mill taken along line B—B inFIG. 4;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1-3 are schematic views showing the commonly used conventionalrolling mills. Due to their structure, it is inevitable for the rolls todeflect during rolling, and this will directly affect the quality of therolled piece. Therefore, the surface precision of the rolled piece,especially the thickness precision of plate, can not meet therequirements.

FIGS. 4-6 show the embodiment of the high-precision rolling mill withflexures being controlled two-dimensionally in accordance with theinvention. As can be seen in FIG. 4, a two-dimensional centralsupporting system comprises a frame 10, middle roll supports 8 and 28,lateral roll supports 6 and 26, pads 5, 25, 7, 27 and 29, and drivingdevices 9. In the frame 10 there are provided the main parts andcomponents such as the upper and lower roll systems, the upper and lowermiddle roll supports 8 and 28, the upper and lower lateral roll supports6 and 26, and etc. The frame 10 can be formed into an integral one, orcan be formed by several parts connected together by means of welding orother connecting methods. The upper and lower roll systems arerespectively composed of a working roll 1 and 21, intermediate rolls 2and 22, and supporting rolls 3, 23 and 4, 24, which form a tower-likeroll system together. The rolled piece is designated by referencenumeral 13. The supporting rolls 3, 23 and 4, 24 at the outermost layerof the roll system are supported in the form of a multi-section beam,generally two or more section beam (refer to FIG. 5), on the upper andlower lateral roll supports 6, 26 and upper and lower middle rollsupports 8, 28. In the central supporting system, the driving devices 9are provided between the upper middle roll support 8 and the upper innerwall of the frame 10, the device 9 is positioned on the upper middleroll support and located at the middle region of the axis of the workingroll, generally located within the length of the roll body of theworking roll. The driving devices 9 can move up and down, causing theupper middle roll support 8 and the upper lateral roll supports 6 tomove together up and down in the integral frame 10 to adjust theclearance between the rolls. For carrying out automatic control, thedriving devices can also be equipped with an automatic sheet thicknesscontrolling device (not shown) so as to accurately detect the magnitudeof the rolling force and the clearance between the rolls. Therefore, theproduction can be automated to obtain high precision products.

Between the lower middle roll support 28 and the lower inner wall of theframe 10 there are disposed horizontal pads 29 (FIG. 4), the horizontalpads are placed under the lower middle roll support and located at themiddle region of the axis of the working roll, generally located withinthe length of the roll body of the working roll. Obviously, the lowermiddle roll support 28 is supported by the horizontal pads 29. Thehorizontal pads 29 can be of different sizes, namely, the thickness ofthe horizontal pads can form a thickness series. The adjustment of therolling line can be realized by using horizontal pads 29 of differentthickness. And also, the horizontal pads 29 can be replaced by ahydraulic device or a screw device.

Referring to FIGS. 4, 5 and 6, it can be clearly seen from FIG. 4 thatthe upper middle roll support 8 is supported vertically by the drivingdevices 9, while the upper lateral roll supports 6 are supportedvertically on the upper middle roll support 8 through pads 7 and canslide in the horizontal direction. Between the upper lateral rollsupports 6 and the frame 10 there are disposed vertical pads 5, thus theupper lateral roll supports 6 press against the frame 10 tightly throughthe vertical pads 5 under the action of the horizontal component force.The driving devices 9, pads 7 and vertical pads 5 are located at themiddle region of the axis of the working roll, being within the lengthof the roll body of the working roll. Similarly, the lower middle rollsupport 28 is supported vertically by the pads 29, while the lowerlateral roll supports 26 are supported vertically on the lower middleroll support 28 through pads 27 and can slide in the horizontaldirection. Between the lower lateral roll supports 6 and the frame 10there are disposed vertical pads 25, thus the lower lateral rollsupports 26 press against the frame tightly through the vertical pads 25under the action of the horizontal component force. The pads 29, 27 andthe vertical pads 25 are located at the middle region of the axis of theworking roll, being within the length of the roll body. The lower rollsupport composed of the lower middle roll support 28, the lower lateralroll supports 26 and the pads 27, together with the pads 29 and verticalpads 25, is supported on the mill frame 10. And the upper roll supportcomposed of the upper middle roll support 8, the upper lateral rollsupports 6 and the pads 7, together with the driving devices 9 and thevertical pads 5, is supported on the frame 10.

Due to the above-mentioned structure of the rolling mill of theinvention, the flexures of the rolls are substantially reduced. This isbecause that the frame, the roll supports, the central supporting meansbetween the middle roll supports and the lateral roll supports, thecentral supporting means between the frame and the middle roll supportsand the central supporting means between the frame and the lateral rollsupports form a two-dimensional central supporting system together,namely providing central support in both vertical and horizontaldirections. And specifically, the upper and lower roll supports of themill, and even the supporting rolls, the intermediate rolls and theworking rolls are all supported centrally in both horizontal andvertical directions. The rolling forces borne by the working rolls aretransmitted to the supporting rolls via the working rolls and theintermediate rolls. The supporting rolls comprise several backingbearings mounted on an mandrel (refer to FIG. 5). Therefore, the outerrings of the bearings rotate when the rolling force is transmitted tothe outer rings, and the rolling force is then transmitted to the uppermiddle roll support and the upper lateral roll supports through thebearings. The vertical component force finally reaches the upper innerwall of the frame via the driving devices, and the horizontal componentforce reaches the side walls of the frame via the vertical pads.Similarly, the rolling force borne by the lower working roll istransmitted to the lower middle roll support and the lower lateral rollsupport via the intermediate rolls and the supporting rolls, with thevertical component force being transmitted to the lower inner wall ofthe frame via the pads 29 and the horizontal component force beingtransmitted to the side walls of the frame via the vertical pads 25. Thedriving devices, the pads and the vertical pads on the forcetransmitting path are all located at the middle region of the axis ofthe working roll, being within the length of the roll body.

Therefore, the rolling mill of the invention guarantees the propershape, namely, the linearity of the generating line of the working rollsnot only in the vertical plane but also in the horizontal plane. As aresult, the flexural deformation of the working rolls do not vary withthe rolling force in the main. Therefore, the rolls flexural deformationis significantly reduced, resulting in the reduction of the thicknesserror of the rolled strips.

The adjustment of the clearance between the rolls is accomplished bymoving the upper middle roll support 8 and the upper lateral rollsupport 6 up and down together in the window of the frame 10, the uppermiddle roll support 8 and the upper lateral roll support 6 are driven bythe driving devices 9.

The rolling mill of the embodiment can be placed upside down, andaccordingly the downward acting driving devices become upward actingdriving devices. Such a modification may have the same effects.

The hydraulic downward acting driving devices can also be replaced by ascrew device.

The pads can be replaced by the bosses or protuberances provided on theframe or the roll supports, and the pads can also be stacked pads.

Compared with the prior art, the invention has the following advantages:

Since the rolling mill of the invention has an integral frame the shapeof which corresponds to the contour outline of the combined rollsupports and the frame is of very high rigidity; the pads or theclearance adjusting devices between the middle roll supports and thelateral roll supports, and the pads between the roll supports and theframe are located in the middle region of the axis of the working rolland are within the length of the roll body of the working roll, and forma two-dimensional automatic central supporting system. Thus, the shapeof the generating line of the working rolls is guaranteed not only inthe vertical plane but also in the horizontal plane. As a result, thebending deformation of the working rolls does not vary with the rollingforce in the main, resulting in the remarkable reduction of thethickness error of the rolled strips.

The rolling mill of the invention can greatly simplify the cambering orthe design of the roll shape and the control of the roll shape duringrolling. The bending deformations of the working rolls of the inventiverolling mill in both the horizontal and vertical directions do not varywith the rolling forces in the main. Since the bending deformation,which is the most important factor among the various factors associatedwith the cambering such as the bending deformation, flatteningdeformation, heat expansion and wear etc., can be left out ofconsideration, and the heat expansion and wear are also slowly changingfactors, the design of the roll shape and the control of the roll shapeduring rolling can be greatly simplified. In addition, the “roll pass”formed by the bending deformations of the two working rolls of aconventional rolling mill is eliminated, thus facilitating thetransverse flow of the metal and being advantageous to rollhigh-precision strips with wedge-shaped blanks, and the phenomenon ofthe “edge attenuation” of strips is greatly improved.

In the above mentioned embodiment of the invention, the number of therolls in the roll system is 12, but the roll systems may have differentnumber of rolls. In addition, the combined roll supports of theinvention can mate with the roll supports or the roll systems in aconventional rolling mill.

The invention is not limited to cold rolling mills, and is alsoapplicable to hot-rolling mills for rolling strips.

Although the preferred embodiments of the invention have been described,to persons skilled in the art, various modifications can be made to theinvention without going beyond the scope of the attached claims of theinvention.

What is claimed is:
 1. A rolling mill for rolling plate and strip,comprising: a mill frame, an upper roll system and lower roll system, anupper roll support and a lower roll support, and a driver operable toadjust the clearance between the rolls, said upper and lower rollsystems being stacked one on top of the other, wherein at least one ofthe roll supports comprises: a first middle roll support, first lateralroll supports located on either side of the first middle roll supportand first central supporting means positioned between said first middleroll support and each of said first lateral roll supports, and whereinsaid first lateral supports are operable to slide laterally in thehorizontal direction relative to said first middle roll support; secondcentral supporting means being disposed between the frame and said firstmiddle roll support, and third central supporting means being disposedbetween the frame and said first lateral roll supports; said first,second and third central supporting means being arranged in the middleregion of the axis of a roll body of a working roll with their lengthsnot longer than that of the roll body of the working roll; said frame,said one of the roll supports, first, second and third central supportmeans together forming a first two-dimensional automatic centralsupporting system; in the operation state of the rolling mill, saidfirst and third central supporting means abut against a correspondingfirst lateral roll support at the central region of the first lateralroll support in the axial direction of the rolls; and said secondcentral supporting means abuts against said first middle roll support atthe central region of the first middle roll support in the axialdirection of the rolls.
 2. The rolling mill as claimed in claim 1,wherein said driver is disposed between the frame and said first middleroll support and is used as said second central supporting means.
 3. Therolling mill as claimed in claim 1, wherein the other of the rollsupports comprises: a second middle roll support, second lateral rollsupports located on either side of the second middle roll support andfourth central supporting means positioned between said second middleroll support and each of said second lateral roll supports, and whereinsaid second lateral roll supports are operable to slide laterally in thehorizontal direction relative to said second middle roll support; fifthcentral supporting means being disposed between the frame and saidsecond middle roll support, and sixth central supporting means beingdisposed between the frame and said second lateral roll supports; saidfourth, fifth and sixth central supporting means being arranged in themiddle region of the axis of the roll body of a working roll with theirlength not longer than that of the roll body of the working roll; saidframe, said other of the roll supports, fourth, fifth and sixth centralsupport means together forming a second two-dimensional automaticcentral supporting system; in the operation state of the rolling mill,said fourth and sixth central supporting means abut against acorresponding second lateral roll support at the central region of thesecond lateral roll support in the axial direction of the rolls; andsaid fifth central supporting means abuts against said second middleroll support at the central region of the second middle roll support inthe axial direction of the rolls.
 4. The rolling mill as claimed inclaim 3, wherein: said fifth central supporting means compriseshorizontal pads; said third and sixth central supporting means comprisesvertical pads which abut tightly against the inner side walls of themill frame and the corresponding side surface of the first and secondlateral roll supports under the action of a horizontal component force,and said first and fourth central supporting means comprise pads.
 5. Therolling mill as claimed in claim 1, wherein said frame is an integralcasting frame, or is assembled to an integral one by welding, with awindow formed in its outer wall.
 6. The rolling mill as claimed in claim1, wherein arranged at an outermost layer of said roll systems aresupporting rolls, the supporting rolls are in a form of a multi-sectionbeam with more than two sections.
 7. The rolling mill as claimed inclaim 2, wherein said driver is hydraulic or electric driving means. 8.The rolling mill as claimed in claim 4, wherein said pads areprotuberances or bosses provided on the frame or the roll supports.